U.S. patent number 6,973,863 [Application Number 10/386,825] was granted by the patent office on 2005-12-13 for adaptor for firing blank ammunition.
This patent grant is currently assigned to FN Herstal. Invention is credited to Corey L. Jones.
United States Patent |
6,973,863 |
Jones |
December 13, 2005 |
Adaptor for firing blank ammunition
Abstract
An adaptor for use with a flash suppressor on a gun barrel in
order to allow the gun to repeatedly fire blank rounds of
ammunition. The adaptor has a stem that chokes the flow of gases
from an exploding round in order to create a back pressure. A body
is used to couple the stem to the flash suppressor and permit a cap
to be threaded to the body. The cap urges the stem into the throat
of the flash suppressor when tightened to the body while the body
grips the flash suppressor to hold the stem and cap in place.
Belleville washers in the cap pre-loaded and urge the stem into the
throat and hold it there securely during repeating firing of the
gun.
Inventors: |
Jones; Corey L. (Lugoff,
SC) |
Assignee: |
FN Herstal (Herstal Beligique,
BE)
|
Family
ID: |
35452414 |
Appl.
No.: |
10/386,825 |
Filed: |
March 12, 2003 |
Current U.S.
Class: |
89/14.2 |
Current CPC
Class: |
F41A
21/26 (20130101); F41A 21/32 (20130101) |
Current International
Class: |
F41A 021/34 () |
Field of
Search: |
;89/14.2,14.4,29,14.5
;42/77 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
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381569 |
|
Oct 1964 |
|
CH |
|
687 392 |
|
Jan 1940 |
|
DE |
|
Primary Examiner: Johnson; Stephen M.
Attorney, Agent or Firm: Mann; Michael A. Nexsen Pruet,
LLC
Claims
What is claimed is:
1. A device for use with a flash suppressor having a tapered
throat, said device comprising: means for choking a flow of gases
from said flash suppressor; a body adapted for gripping said flash
suppressor; and a cap threadedly secured to said body and adapted
for holding said choking means in said flash suppressor, said cap
including at least one spring washer for urging said choking means
into engagement with said tapered throat of said flash suppressor
and said cap to said body when said body is coupled to said flash
suppressor and said cap is secured to said body.
2. The device as recited in claim 1, wherein said at least one
spring washer is at least one pair of spring washers.
3. The device as recited in claim 1, wherein said flash suppressor
has a face and wherein said body has a flange oriented radially
inward and adapted to engage said face of said flash
suppressor.
4. A device for use with a flash suppressor having a tapered
throat, said device comprising: means for choking a flow of gases
from said flash suppressor; a body adapted for gripping said flash
suppressor; and a cap threadedly secured to said body and adapted
for holding said choking means in said flash suppressor, said cap
including at least one spring washer for urging said choking means
into engagement with said tapered throat of said flash suppressor
and said cap to said body when said body is coupled to said flash
suppressor and said cap is secured to said body, wherein said at
least one spring washer is at least one pair of spring washers,
each spring washer of said at least one pair of spring washers
being oriented to oppose said other spring washer of said at least
one pair of spring washers.
5. A device for use with a flash suppressor having a rearward face
and a tapered throat, said device comprising: a body having means
formed thereon for engaging a rearward face of said flash
suppressor and dimensioned to receive said flash suppressor
therein; a stem carried in said body and having a first end and an
opposing second end, said first end being dimensioned to be
receivable in said tapered throat of said flash suppressor; and a
cap, said cap being threadedly secured to said body, said cap
including at least one spring washer for urging a choking means
into engagement with said tapered throat of said flash suppressor
when said body is coupled to said flash suppressor and said cap is
secured to said body.
6. The device as recited in claim 5, wherein said first end of said
stem is tapered.
7. A device for use with a flash suppressor having a rearward face
and a throat, said device comprising: a body having means formed
thereon for engaging a rearward face of said flash suppressor and
dimensioned to receive said flash suppressor therein; a stem
carried in said body and having a first end and an opposing second
end, said first end being dimensioned to be receivable in a throat
of said flash suppressor; and a cap being threadedly secured to
said body, said cap including at least one spring washer for urging
a choking means into engagement with said flash suppressor when
said body is coupled to said flash suppressor and said cap is
secured to said body, wherein said at least one spring washer
comprises at least one pair of spring washers, each spring washer
of said at least one pair of spring washers being oriented to
oppose another spring washer of said at least one pair of spring
washers.
8. The device as recited in claim 7, wherein said at least one
spring washer further urges said choking means into engagement with
a flange of said body extending radially inward of said body.
9. The device as recited in claim 7, wherein said stem has a flange
between said first end and said second end, and said at least one
spring washer further comprises a spring means for urging said
first end of said stem into said throat of said flash suppressor,
said spring means bearing on a flange of said stem.
10. The device as recited in claim 7, wherein said second end has
an annular recess formed therein and said cap has a hole formed
transverse to the axis of said stem, said cap further comprising a
pin inserted in said cap so that said pin rides in said annular
recess.
11. The device as recited in claim 7, wherein said cap has opposing
flat surfaces formed thereon and adapted to be gripped by a
wrench.
12. A device for use with a flash suppressor, said device
comprising: a stem having a tapered first end and an opposing
second end, said tapered end dimensioned to be received in said
flash suppressor, said flash suppressor having a side and an end,
said tapered first end of said stem being receivable in said end of
said flash suppressor, said stem having a bore formed therein and
dimensioned for choking the path of combustion gases escaping from
said end of said flash suppressor and creating a back pressure
required for chambering a next round; a body adapted to grip said
flash suppressor, said body having an opening formed therein and
dimensioned to receive said side of said flash suppresser therein
when said flash suppressor is brought into engagement with said
body; a cap threadably attached to said body, said cap having
opposing faces formed thereon and adapted for receiving a wrench
for tightening said cap to said body; and plural spring washers
carried within said cap in engagement with said stem, said plural
washers urging said stem into engagement with said end of said
flash suppressor when said cap is tightened to said body and said
body grips said flash suppressor.
13. The device as recited in claim 12, wherein said plural spring
washers are sets of spring washers arranged in pairs of opposing
spring washers.
14. The device as recited in claim 12, wherein said body has a
flange, said flange being in engagement with said flash suppressor,
and wherein said body is cylindrical and said opening leaves about
180.degree. of contact between said flash suppressor and said
flange of said body.
15. The device as recited in claim 12, further comprising means
carried by said cap for limiting axial movement of said stem with
respect to said cap.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A MICROFICHE APPENDIX
Not applicable.
BACKGROUND OF THE INVENTION
So-called "blank" ammunition consists of shell casings loaded with
gun power or other explosive but without projectiles. When fired, a
blank round sounds much like "live" ammunition but, unlike live
ammunition, no projectile leaves the barrel of the gun in which the
blank was fired. Blank ammunition is used extensively in military
training for safety reasons.
In the case of a gas operated automatic rifle or machine gun a
portion of the gas pressure created inside a gun's barrel by the
ignition of a cartridge is diverted through a small hole in the
barrel to be utilized for the operation of the gun's mechanism that
ejects the spent cartridge case and loads a live one from the gun's
magazine. In the case of the firing of a "blank" there is less gas
pressure built up in the barrel because there is no projectile
being forced through the barrel. The lower gas pressure in the
barrel causes the diverted gas to be of too low a pressure to
properly operate the gun's ejection and loading mechanism.
Typically, an adapter is fitted onto the end of the barrel that
restricts the flow of gas and increases the pressure in the barrel
to a level that equals the pressure created when a "live" cartridge
is fired. Thus the adapter allows a gun firing blank ammunition to
operate in the same way as the gun would when firing "live"
ammunition.
Existing blank adapters were designed to work with older model
machine guns such as the M240, which normally operate under
moderate firing schedules. There is a significant and adverse
impact on the life of the older design of the blank firing adapter
when used on newer, shorter and lighter weight machine guns, such
as the Mark 48. The newer, lighter guns operate at accelerated
firing schedules and are configured with shorter and lighter
barrels, which create increased temperatures. The increased
temperatures seen at the muzzle of newer lightweight guns damage
the blank adapter made to the older design. The temperatures
developed at the muzzle end of the barrel exceed the design
parameters for the older blank firing adapter and consequentially
reduce its life from 7,000 rounds to 500 rounds. This diminution of
blank firing adapter life is unacceptable for its use on a new type
machine gun.
Another problem with blank firing adapters is that as the muzzle
end of the barrel heats up, the blank firing adapter heats
unevenly, causing the adapter to loosen. When the adapter loosens,
gas escapes around the tapered end of the stem, causing a reduction
in pressure inside the barrel and damage to the adapter. The
reduction in pressure consequently reduces the amount of diverted
gas below the level required for the proper operation of the gun's
mechanism. When it loosens the operator must stop and re-tighten
the adapter using a special tool. Typically, re-tightening the
existing adapter on an older style gun is required around 1,000
rounds. For a new style gun it is required almost immediately.
ADAPTOR
Ideally, there would be an adaptor for a barrel of a machine gun of
either the older or newer design that allows it to fire blank
ammunition in a manner similar to that of live ammunition but
without damage to or loosening of the adaptor. Such an adaptor
should also be easier to maintain and not require special tools for
installation or tightening.
SUMMARY OF THE INVENTION
Briefly recited and according to its major aspects, the present
invention is an adaptor for use with a machine gun. The present
adaptor comprises a stem that is dimensioned to fit into the
machine gun barrel, thus reducing its effective barrel internal
diameter in order to create sufficient backpressure, a body that
grips the barrel and surrounds the stem, and a cap that holds the
stem securely to the body. The cap also includes a set of
Belleville washers arranged to hold the stem in a preloaded
condition against the flash suppressor so that tightening during
use is not required.
An important feature of the present invention is the use of the
Belleville washers to help hold the stem firmly in place in the
barrel of the machine gun. As a result, the present adaptor enables
a barrel of a newer machine gun to fire 7000 rounds or more.
Another important feature of the present invention is the pair of
opposing faces formed on the cap that can receive the jaws of the
same wrench that tightens the gas regulator. Thus, one wrench can
be used to install the blank adaptor and the gas regulator; no
additional wrench is required.
These and other features and their advantages will be apparent to
those skilled in the art of firearms from a careful reading of the
Detailed Description of Preferred Embodiments accompanied by the
following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 illustrates in perspective the end of a barrel of a machine
gun with a typical flash suppressor on the end, according to the
prior art;
FIG. 2 illustrates in perspective the end of a barrel of the same
machine gun with its flash suppressor and having a blank adaptor
according to a preferred embodiment of the present invention
attached thereto;
FIG. 3 is a cross sectional view of the barrel, flash suppressor
and blank adaptor of FIG. 2, taken along lines 3--3;
FIG. 4 is a partially exploded view of the barrel, flash suppressor
and blank adaptor shown in FIG. 2;
FIG. 5 is an exploded view of the blank adaptor, according to a
preferred embodiment of the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention is a blank adaptor for use with a machine
gun. The adaptor is intended to create a sufficient backpressure in
the barrel of a gun for use in ejecting a fired cartridge and
chambering a subsequent round of ammunition. While the present
blank adaptor embodiment has particular utility with a US military
machine gun designated as the Mark 48, it is also suitable for use
with other machine guns and indeed guns other than machine guns
with only minor modifications in dimensions.
FIG. 1 illustrates a portion of a prior art gun barrel with a flash
suppressor attached to the end thereof. Neither the barrel nor the
flash suppressor is part of the present invention. However, the
present invention is made to be used with a barrel having a feature
on the end thereof, such as the flash suppressor shown, that
provides a gripping surface, preferably one lying in the plane
defined by the barrel's axis and facing rearward, that is, away
from the muzzle end of the barrel.
FIG. 1 shows a barrel 10 with a flash suppressor 12 having a rear
surface 14 and plural vent holes 16. FIG. 2 illustrates in
perspective the same barrel 10 and flash suppressor 12 as shown in
FIG. 1. Additionally, FIG. 2 shows a blank adaptor 20 attached to
flash suppressor 12. FIGS. 3-5 illustrate various details of how
the present blank adaptor 20 is constructed and installed on barrel
10 with flash suppressor 12.
Blank adaptor 20 includes a body 22 and a cap 24. Through the vent
holes 16 of flash suppressor 12 a stem 26 is also visible, at least
in part. Stem 26 is also part of blank adaptor 20. Body 22 has an
opening 30 that allows it to be brought into engagement with flash
suppressor 12 from the side rather than slipped over it from the
end. Body 22 has a gripping flange 32 that extends radially inward
of body 22 to couple to and engage rear surface 14 of flash
suppressor 12, when body 22 is applied to flash suppressor 12. The
engagement of gripping flange 32 and rear surface 14 is important
to the operation of the present blank adaptor 20. The pressure of
the gases from firing a blank round pushes forward, that is, toward
the muzzle end of barrel 10 and therefore against blank adaptor 20.
The engagement of these two components, namely, gripping flange 32
of body 22 and rear surface 14 of flash suppressor 12, resists this
pressure and allows blank adaptor 20 to remain in place on barrel
10. Gripping flange 32 preferably extends approximately halfway
around flash suppressor 12, as body 22 straddles flash suppressor
12, so that there is approximately 180.degree. of contact between
it and rear surface 14. Thus, body 22 can easily be installed on
flash suppressor 12 from the side but nevertheless provides
sufficient surface-to-surface contact between gripping flange 32
and rear surface 14 within that 180.degree. of engagement.
Body 22 has a threaded end 34 opposite gripping flange 32. Threaded
end 34 has external threads 36 that mate with internal threads 38
of cap 24. Cap 24 can thus be threadedly secured to body 22.
Stem 26 is hollow, with an internal bore 40 that is smaller in
internal diameter than the internal bore 42 of barrel 10. Stem 26
has a tapered first end 44, a flange 46 and an annular recess 48 at
a second end 50 that opposes first end 44. It will be clear from
FIG. 3 that flash suppressor 12 has a tapered throat 60. Tapered
first end 44 of stem 26 is dimensioned to match the taper of throat
60 of flash suppressor 12 for good fit. Stem 26, when tapered first
end 44 is in full engagement with tapered throat 60, is long enough
so that second end 50 extends from flash suppressor 12. The
reduction in internal diameter between barrel 10 and stem 26, when
stem 26 is in place in flash suppressor 12, chokes the path of
escaping combustion gases and creates the backpressure required to
chamber the next round.
Body 22 has an internal bore 62 dimensioned to receive second end
50 of stem 26, but bore 62 is not large enough to allow flange 46
of stem 26 to pass. Body 22 has an annular recess 66 dimensioned to
receive flange 46, which is positionable between first end 44 and
second end 50. Flange 46 interacts with features of cap 24, as will
now be explained.
Cap 24 has a large internal bore 70 and carries internal threads
38. Internal bore is dimensioned to receive second end 50 of stem
26. Cap 24 contains plural washers 72, preferably eight spring
washers or "Belleville" washers arranged in pairs. Washers 72
receive second end 50 and, when cap 24 is tightened, bear against
flange 46, which is designed to distribute and transfer the load of
the washers to stem 26. As cap 24 is threaded to threaded end 34 of
body 22, stem 26 is urged against tapered throat 60 by the load
applied on flange 46 by washers 72 in cap 24. Internal threads 38
of cap 24 hold cap 24 to external threads 36 of body 22, while body
22 is held securely by gripping flange 32 to rear surface 14 of
flash suppressor 12. Washers 72 are formed to have a center in a
different plane than their periphery so that they resist loosening
but can be tightened and, when tightened, the two planes move
together. Washers 72 are preferably arranged in opposing pairs;
that is, one washer is oriented to oppose the other rather than to
"nest" in the other.
Two pins 76 are inserted transverse to the axis of stem 26 and just
off-axis so that they fit into annular recess 48 of second end 50.
Pins 76 prevent axial movement of stem 26 beyond the axial limits
of annular recess 48. Opposing flat surfaces 78 allow a wrench to
be applied to cap 24 for tightening or loosening. Preferably, flat
surfaces 78 are spaced apart a distance just sufficient for a gas
regulator wrench so that the gas regulator wrench can be used to
turn cap 24.
Those skilled in the art of firearms will readily appreciate that
many substitutions and modifications can be made to the foregoing
description of preferred embodiments without departing from the
spirit and scope of the present invention, which is defined by the
appended claims.
* * * * *